1. Field of the Invention
The present invention relates to a colorant-containing curable composition that is suitable for forming a color filter for use with a liquid crystal display device, a solid-state image pickup element and the like, a color filter containing the colorant, and a method for manufacturing the same.
2. Description of the Related Art
In the field of dyes the development of compounds which have high color fastness, with both light resistance and heat resistance, have been desired, and earnest investigations have been undertaken. Particularly desired has been the development of compounds that show both light resistance and heat resistance in the field of dyes that are soluble in solvents or water.
As superior dyes which exhibit both light and heat resistance, phthalocyanine compounds and Cr complexes of azo dyes are known. However, phthalocyanine compounds cannot be used for yellow or magenta dyes, since they are inappropriate for the purpose of visible absorption at 400 to 500 nm. Also, since phthalocyanine compounds show high light resistance due to their molecular association, when dissolved in water or solvents they show storage stability problems such as precipitating out.
Cr complexes of azo dyes have been shown to be damaging to people, living bodies and the environment, since they contain Cr atoms, and so amelioration thereof is highly desired. On the other hand, azo dyes have high color values, and are dyes that are useful for obtaining a variety of absorption wavelengths. However, non metallic-complex type compounds which demonstrate, at the same time, both satisfactory high light resistance and heat resistance have not yet been seen.
Among these, known azo dyes which are comparatively lightfast are compounds with a coupling component of γ acid (such as for example Acid Red 57) and, compounds which use pyrazolone (such as Acid Yellow 29). However, azo dyes that are able to obtain, at the same time, both satisfactory light resistance and heat resistance have not yet been seen (for example refer to Polish Patent Invention No. 101484, West German Patent No. 2714204, French Patent Invention No. 2303839 and Japanese Patent Application Laid-Open (JP-A) No. 58-152240).
Also, there is the problem that the heat resistance and light resistance of these dyes can be dramatically reduced depending on the conditions of use. For example, according to the following factors the heat resistance, the light resistance, or both is sometimes reduced: the type of fibers dyed; the presence of other coloring compounds, photopolymerization initiators, polymerizable compounds, acidifiers/reduction agents and the like; whether is it in an environment where ozone can develop; or an environment where singlet oxygen can develop.
Further, since a reduction is common of the solubility in water or solvent of dyes that demonstrate high light resistance and heat resistance, there are many problems with the widespread use of these pigments in industry.
In recent years, for applications such as solid image pickup elements, higher precision of the color filter has been demanded. However, it is difficult to further improve the resolution with the conventional pigment dispersion system. In addition, there are problems, such as irregular color being caused by coarse particles of the pigment. Therefore, the above-mentioned pigment dispersion method has not been suited for applications such as solid image pickup elements where extremely fine patterns are required.
In order to solve the above-mentioned problems, examples where a solvent or water soluble dye is used have been conventionally known (see, for example, JP-A No. 2002-278056).
However, the dye-containing curable composition has the following problems (1) to (4).                (1) Generally, coloring matter has a low solubility in either alkali water solutions or organic solvents, thus it is difficult to obtain a liquid curable composition having the desired spectrum.        (2) Dyes often interact with other components in the curable composition, thus it is difficult to adjust the solubility of the curing part and the non-curing part (developability).        (3) When the dye has a low molar absorption coefficient (ε), the dye must be added in a large quantity, thus it is inevitable that the amounts of the other components in the curable composition, such as the polymerizable compound (monomer), the binder, and the photopolymerization initiator, must be reduced. This presents such problems as the lowering of the curability of the composition, the heat resistance after curing, and the developability of the (non-)curing part.        (4) Dyes are generally inferior in light resistance and heat resistance, as compared to pigments.        
In addition, especially for the application for manufacturing of a color filter for a solid image pickup element, it is required that the film thickness be 1.5 μm or less, unlike in semiconductor manufacturing applications. Therefore, the coloring matter must be added to the curable composition in a large quantity, which presents the same problems as mentioned above.
Also, the use of pyridone azo dyes in curable compositions has been published in the past, but these known pyridone azo dyes have the problem of being low in both heat resistance and solvent solubility (see, for example, JP-A No. 2002-14221).
Because of the above-mentioned problems, it has been difficult in practice to meet the requirements for performance for use in extremely fine, thin-film colored patterns for high-precision color filters.
Therefore, development of a dye and curable composition which can eliminate the above-mentioned problems has been desired.